Pushbutton type mechanical pencil

ABSTRACT

A PUSHBUTTON TYPE MECHANICAL PENCIL COMPRISING AN OUTER HOLDER MAIN BODY, AN INNER CYLINDRICAL HOLDER MEMBER STATIONARILY DISPOSED WITHIN SAID OUTER MAIN BODY, A TIP MEMBER CONNECTED TO SAID INNER CYLINDRICAL HOLDER MEMBER AT THE LOWER END OF THE LATTER, A LEAD GUIDE TUBE SLIDABLY RECEIVED WITHIN SAID TIP MEMBER, AN ELASTIC MEMBER DISPOSED AROUND SAID LEAD GUIDE TUBE FOR HOLDING A LEAD IN SLIGHT FRICTIONAL ENGAGEMENT WITH SAID LEAD GUIDE TUBE, A DEPRESSIBLE LEAD PUSHER MEMBER RECEIVED IN SAID OUTER HOLDER MAIN BODY AT THE TOP THEREOF, A CHUCK OPERATIVELY CONNECTED TO SAID PUSHER MEMBER AND ADAPTED TO GRIP SAID LEAD AND LEAD GUIDE TUBE, AND A CLUTCH RECEIVED IN SAID INNER HOLDER MEMBER FOR GRIPPING AND RELEASING SAID CHUCK, SAID CHUCK HAVING A LEAD PASSAGE AND AN AXIALLY ALIGNED RECESS WHICH IS ADAPTED TO GRIP THE UPPER PORTION OF SAID LEAD GUIDE TUBE.

May 23, 1972 TATsUzO MINAGAWA 3,664,753

PUSHBUTTON TYPE MECHANICAL PENCIL Filed July lO, 1970 3 Sheets-Sheet l ATTORNEYS May 23, 1972 TATsuzo MINAGAWA PUSHBUTTON TYPE MECHNICL PENCIL 5 Sheets-Sheet 2 Filed July l0, 1970 1E. EA-

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May 23, 1972 TATsUzo MINAGAWA 3,664,753

PUSHBUTTON TYPE'MECHANICAL PENCIL Filed July lO, 1970 3 Sheets-Sheet 5 BYWIJ *l ATTORNEYS United States Patent O PUSHBUTTON TYPE MECHANICAL PENCIL Tatsuzo Minagawa, 637 Tahata-cho,

Kitaku, Tokyo, Japan Filed July 10, 1970, Ser. No. 53,791 Claims priority, application Japan, July 18, 1969,

ATM/68,304; Aug. 14, 1969, 44/77,602

Int. Cl. B43k 21/16, 21/20 U.S. Cl. 401-65 7 Claims ABSTRACT OF THE DISCLOSURE A pushbutton type mechanical pencil comprising an outer holder main body, an inner cylindrical holder member stationarily disposed within said outer main body, a tip member connected to said inner cylindrical holder member at the lower end of the latter, a lead guide tube slidably received within said tip member, an elastic member disposed around said lead guide tube for holding a lead in slight frictional engagement with said lead guide tube, a depressible lead pusher member received in said outer holder main body at the top thereof, a chuck operatively connected to said pusher member and adapted to grip said lead and lead guide tube, and a clutch received in said inner holder member for gripping and releasing said chuck, said chuck having a lead passage and an axially aligned recess which is adapted to grip the upper portion of said lead guide tube.

BACKGROUND OF THE INVENTION In a conventional pushbutton type mechanical pencil in which a lead guide or protection tube extends within the tip member of the holder main body of the pencil and the lead guide tube is adapted to extend beyond the end of the tip member so as to protect a lead received in the lead guide tube from any impact or external force which will otherwise subject the lead to breakage, if the lead guide tube is allowed to remain in its extended position beyond the end of the tip member when the pencil is not used, when the lead guide tube is subjected to any impact or external force as experienced in the case in which the pencil is accidentally dropped or hits against a hard article the lead guide tube may sustain damage and/or bend to the extent that the pencil will be rendered unsuitable for its intended purpose.

SUMMARY OF THE INVENTION This invention relates to a mechanical pencil and more particularly, to a pushbutton type mechanical pencil which incorporates improved protection means for a lead and its guide tube.

One object of the present invention is to provide a pushbutton type mechanical pencil of the type in which when the pencil is not used, a lead and its guide tube can be easily and simply retracted within the tip member of the holder main body of the pencil thereby to effectively protect the lead and lead guide tube from any external force or impact which may otherwise subject the lead and tube to damage and/or bending.

Another object of the present invention is to provide a pushbutton type mechanical pencil of the type in which the retraction of the lead and lead guide tube into the tip member is effected by the retraction of a chuck which is adapted to grip and advance the lead when the lead is to be retracted.

According to the present invention, there has been provided a pfushbutton type mechanical pencil which cornprises a hollow holder main body and having open opposite ends, an inner cylindrical holder member stationice arily received in said main body and having open opposite ends in communication with said opposite ends of the main body, respectively, a hollow tip member removably connected to one of said opposite ends of the main body, a lead guide tube slidably received in said tip member and receiving a lead so as to permit the lead to slidably move therein, an elastic member disposed on said lead guide tube for frictionally urging said lead against said lead guide tube with a slight force, a pusher member removably received in said main body at the other of said opposite ends of the main body, a chuck operatively connected to said lead pusher member for gripping and releasing said lead, and a clutch received in said tip member over said chuck for gripping and releasing the chuck, said chuck having a recess formed at one end thereof in axial alignment with the center bore in the chuck.

The above and other objects and attendant advantages of the present invention will be more apparent to those skilled in the art from reading the following detailed description in conjunction with the accompanying drawings in which one preferred embodiment of the invention is shown for illustration purpose only, but not for limiting the scope of the same.

BRIEF DESCRIPTION O'F THE DRAWINGS FIG. 1 is an elevational view in partial section of one preferred embodiment of push button type mechanical pencil of the present invention showing portions of the pencil in section;

FIG. 2A is a fragmentary longitudinal sectional view on an enlarged scale of the middle portion of said pencil with parts associated with the portion removed therefrom;

FIG. 2B is a fragmentary longitudinal sectional view on an enlarged scale of the lower portion of said pencil;

FIG. 3 is similar to FIG. 2B, but especially shows the writing element or lead and its guide tube in their retracted position;

FIG. 4 is a fragmentary longitudinal sectional view on a further enlarged scale of a lead gripping chuck;

FIG. 5 is a bottom view 0f FIG. 4;

FIG. l6 is a fragmentary longitudinally sectional view on an enlarged scale of Said lead, guide tube and an elastic member showing the lead as being held in position within said guide tube by said elastic member; and

FIG. 7 is a cross-sectional view taken substantially `along the line VII-VII of FIG. 6.

PREFERRED EMBODIMENT OF THE INVENTION r The present invention will be now described referring to the accompanying drawings and more particularly, to FIGS. 1 and 2 thereof. In these figures, reference numeral 1 denotes the holder main body which of the push button type mechanical pencil tapers towards the opposite ends which are open and has an annular shoulder 1 formed in the inner periphery adjacent to and inwardly spaced from the lower end of the holder main body (as seen in FIGS. 1 and 2). An inner cylindrical holder member 2 is stationarily received in the main body 1 and has a radially and outwardly extending annular dange 2 formed at a point between the opposite ends thereof. The lower end of the annular flange 2 of the inner cylindrical holder member 2 (as seen in LFIGS. 1 and 2) seats on the annular shoulder 1 in the holder main body 1. The lower end portion of the inner holder member 2 extends beyond the lower end of the main body 1 and has threads 3 formed in the outer periphery. A tubular tip member 4 which tapers towards the lower' end (as 4seen in IFIGS. 1 and 2),

3 is threaded at the upper end on the threaded lower end portion 3 of the inner holder member 2 and extends downwardly of the holder member 2. The tip member 4 has a stepwise reduced diameter interior to provide four annular shoulders 4', 4", 4 and 4" in the inner periphery for the purpose to be described hereinafter. The uppermost shoulder 4 has a largest diameter and the subsequently lower shoulders 4, 4" and 4 have subsequently reduced diameters on the order. A writing element or lead passage member 5 is provided within the holder main body 1 With the lower end portion of the member (as seen FIG. 2A) slidably received within the inner holder member 2 and the lead passage member has a through center bore 5 which has an enlarged diameter threaded lower portion for the purpose to be described hereinafter. The upper portion of the lead passage feed member 5 (as seen in FIG. 2A) extends upwardly beyond the upper end of the inner holder member 2 and is connected to the lower end portion of a tubular spare lead reservoir 6 (as seen in FIG. 2A) the upper end of which (as seen in FIG. 2A) terminates short of the upper end of the holder main body 1. A removable lead pusher member 7 in the form of a short tube having the closed top and open bottom is received in the open upper end portion of the lead reservoir 6. The above-mentioned inner holder member 2 also has an inner flange 2" adjacent to and spaced from the lower end radially and inwardly extending from the inner-periphery of the member and a helical spring S is disposed in a compressed state within the holder member 2 with the lower end abutting against the annular flange 2" while the upper end abutting against the lower end lof the lead passage member 5 so as to normally urge the passage member, lead reservoir and lead pusher upwardly to the extent that the lead pusher member 7 will be extended beyond the open upper end of the holder main body 1, Reference numeral 9 denotes a hollow lead retaining chuck having a plurality of angularly spaced slits 10 formed in the peripheral wall extending vertically from the lower end and terminating short of the upper end as shown in FIGS. 4 and 5 (as seen in FIG. 2B). The chuck 9 is imparted thereto an elasticity by the provision of the slits 10. The chuck has a center bore having a reduced diameter portion 21 between the opposite ends and the reduced diameter bore portion 21 has a diameter substantially corresponding to that of the lead to permit the lead to slidably pass therethrough. The chuck 9 also has a recess 22 formed at the bottom end in vertical alignment and communication with the center bore 20, 21 for the purpose to be described hereinafter. The chuck 9 includes a reduced diameter upper portion 9' which is surrounded by the helical spring 8 and formed at the upper end in the outer periphery with threads 11 for meshing with the threaded lower portion of the lead passage member 5. A reversed cup-shape clutch 12 is loosely received within the lower portion of the inner holder member 2 over the chuck 9 for gripping and releasing the chuck in the manner as will be described hereinafter. The top wall of the clutch has a center opening through which the reduced diameter upper portion 9 of the chuck 9 extends. Reference numeral 13 denotes writing element or lead and reference numeral 14 denotes a tubular lead guide which extends within the tip member 4 and the upper end portion of which is adapted to be gripped by and released lfrom the chuck 9 in the manner mentioned hereinafter. The diameter of the tubular lead guide 14 substantially corresponds to that of the smallest diameter lowermost portion of the hollow interior of the tip member 4 so that when the lead guide tube having the lead received therein is extended beyond the lower end of the tip member for writing operation, the guide tube will be laterally stabilized. The diam eter of the hollow interior of the lead guide tube 14 substantially corresponds to the diameter of the lead 13 to permit the lead to slidably pass therethrough. The lead guide tube 14 has an opening 16 in the peripheral wall at a point between the opposite ends as shown in FIGS. 6

and 7 for receiving an annular rubber member 17 which is snugly litted on the guide tube 14 and adapted to apply an elastic force on a portion of the lead 13 which exposes through the opening 16 to the rubber member so as to frictionally hold the lead in position within the lead guide tube 14 when the lead and guide tube are moved in unison. A sleeve member 18 is disposed on the upper portion of the lead guide tube 14 and integrally attached thereto by any suitable means and the sleeve member is adapted to slidably pass through a bushing 19 which is in turn held in position within the tip member 4 and has a radially and outwardly extending flange 119' at the top which seats on the shoulder 4 in the tip member 4. The upper surface of the flange 19 tapers upwardly for the purpose to be described hereinafter. The sleeve member 18 is flared at the lower end as shown with reference numeral 18 so that the sleeve may be prevented from accidentally slipping out of the bushing 19. The above-mentioned annular rubber member 17 may be replaced by any other suitable elastic member such as an elastic lip which may be formed with a metal tube fitted on the lead guide tube 14 without departing from the scope of the present invention.

In use, it is assumed that the lead guide tube 14 and lead 13 rmly held within the tube are disposed in the position as shown in FIG. 3 in which the lower ends of tips of the guide tube and lead are flush with the lower end of the tip member 4 and the upper end portion of the guide tube is elastically gripped by the chuck 9. When the pusher member 7 is manually depressed down against the force of the helical spring 8, the lead reservoir 6, lead passage member 5, chuck 9, clutch 12 and lead guide tube 14 are moved downwardly in unison and accordingly, the lead guide tube 14 having the lead 13 received therein which is then elastically gripped by the chuck 9 through the sleeve member 18 is also moved downwardly. The rubber member 17 on the lead guide tube 14 is also moved down together with the tube and lead. As the assembly is moved downwardly in the manner mentioned just above, when the lower end of the clutch 12 seats on the uppermost shoulder 4 in the tip member 4, the clutch 12 releases its grip on the chuck 9 and the assembly is caused to move downwardly by gravity leaving the clutch 12 on the shoulder 4. As the assembly except the clutch 12 moves downwardly by gravity, the lower end of the rubber member 17 seats on the lowermost shoulder 4" in the tip member 4 and the lower end portion of the lead guide tube 14 extends beyond the lower end of the tip member 4 by a predetermined amount suitable for writing operation. If the amount of the lead 13 extended beyond the lower end of the lead guide tube 14 is then shorter than a predetermined amount suitable for writing operation, the user presses the pusher member 7 once or more to advance the lead until the extended amount of the lead reaches the predetermined suitable amount. On the other hand, the extended amount of the lead 13 is too excessive for proper writing or greater than the predetermined amount, the user pushes the extended lead against a hard article to retract the lead within the lead guide tube 14 until the extended lead amount reaches to the proper one for writing. The extending and retracting movement of the lead 13 is effected relative to the lead guide tube 14 against the elastic force of the annular rubber member 17 which urges the lead against the guide tube. As the extending or exposed amount of the lead 13 is `gradually consumed while the writing operation continues, the lead guide tube 14 is proportionally pushed upwardly or retracted within the tip member 4 by a writing pressure which will be developed by the contact of the tip of the lead guide tube 14 with the surface of a paper on which the writing operation is being made. Thus, the extended amount of the lead 13 beyond the lower end of the lead guide tube 14 can be always maintained until almost the whole amount of the initially extended lead portion the particular lead 13 is consumed without the necessity for additional pushing-down of the lead by the pusher member 7 and accordingly, the writing operation can be continued for a longe-r writing without interruption than by any of the conventional ever-sharp pencils.

Arfter the particular Writing operation has completed, the -user presses the tip end of the lead guide tube 14 or both the tip ends of the guide tube and lead if any extended amount of the lead is left at the time against the surface of a hard article available at hand so as to retract the guide tube having the remaining lead therein into the tip member 4 until the upper end of the sleeve 18 is received into the recess 22 at the bottom of the chuck 9 which is in turn again gripped by the clutch 12 which is then again urged upwardly by the helical spring 8 and thus, the assembly of the movable parts again assumes the position as shown in FIG. 3 in which the lower end of the lead guide tube having the lead received therein becomes tlush with the lower end of the tip member 4 whereby the lead guide tube can lbe effectively protected from an impact or force which will otherwise subject the tube to breakage and/or bending if the lower end of the tube is left exposed out of the tip member.

While only one preferred embodiment of the invention has been shown and described in detail it will be understood that the same is for the purpose of illustration only and is not to be taken as a definition of the scope of the invention, reference being had for this purpose to the appended claims.

What is claimed is:

1. A pushbutton type mechanical pencil which comprises a hollow holder` main body having open opposite ends, an inner cylindrical holder member stationarily received in said main body and having open opposite ends in communication with said opposite ends of the main body, respectively, a hollow tip member removably connected to one of said opposite ends of the main body, a lead guide tube slidably received in said tip member and receiving a lead to permit the lead to slidably move therein, an elastic member disposed on said lead guide tube for frictionally urging said lead against said lead guide tube with a slight force, a pusher member received in said main body at the other of said opposite ends of the main body, a chuck operatively connected to said lead pusher member for gripping and releasing said lead, and a clutch received in said tip member over said chuck for gripping and releasing said chuck, said chuck having a recess formed at lower end thereof in axial alignment with the center bore in the chuck for gripping and releasing upper end of said lead guide tube.

2. Pushbutton type mechanical pencil as set forth in claim 1, in which a sleeve member is integrally attached to said lead guide tube and slidably received in a bushing xedly secured to said tip member and one end of said sleeve member is adapted to be gripped by said chuck at said recess of the chuck.

3. A pushbutton type mechanical pencil as set forth in claim 1, in which said pencil includes means for retaining said lead guide tube in a position extending by a predetermined distance from one end of said tip member.

4. A pushbutton type mechanical pencil as set forth in claim 1, in which said sleeve member has a detention portion at one end thereof which is adapted to engage one end of said bushing so as to prevent the sleeve member from slipping out of the bushing.

5. A pushbutton type mechanical pencil as set forth in claim l1, in which said lead guide tube has an opening in its peripheral wall and said lead is exposed to said elastic member through said opening to be urged into frictional engagement with the lead guide tube thereby.

6. A pushbutton type mechanical pencil as set forth in claim 1, in which said elastic member comprises an annular rubber tube disposed on said lead guide tube.

7. A pushbutton type mechanical pencil as set forth in claim 1, in which said elastic member comprises an elastic lip formed with an annular metallic member disposed on said lead guide tube.

References Cited UNITED STATES PATENTS 2,109,604 3/ 1938 Van Norsdall 401-53 2,484,640 10/ 1949 Mustard 401-67 3,424,535 1/1969 Schischkow 401-53 3,537,799 11/1970 Sakamoto 401--67 LAWRENCE CHARLES, Primary Examiner 

